It is known in the art that there are many applications wherein two reactive components must be mixed just prior to using. For example, the well-known epoxy adhesives are two-component systems, consisting of an epoxy resin and an amine hardener which are mixed and then utilized to bond various substances, such as wood, metal, etc. It would be desirable to be able to apply this adhesive without going through the step of mixing, since mixing wastes, consumes time and labor and is subject to various human errors. At present there is no one-package epoxy adhesive system which has achieved commercial utility and which is suitable for the consumer market.
It is known in the art to encapsulate reactants in micro-capsules having solid walls. For example, carbonless paper, as developed by The National Cash Register Co., utilizes microencapsulated dyes, which are coated on the paper, and subsequently ruptured by the pressure of a typewritter key. See Chemical Engineering, December 4, 1967, pp. 171-178.
Other examples of solid encapsulated systems, include (1) solvent reactivated adhesives, wherein neoprene is mixed with encapsulated toluene and the adhesive action is developed by rupturing the capsules and allowing the toluene to mix with the neoprene; and (2) encapsulated flavors and fragrances wherein the flavor or fragrance is released by rupture of the capsules.
In the past, emulsions have been used in separation processes to encapsulate reactants. In this process an emulsion comprising an interior and surfactant-containing exterior phase is contacted with a feed stream which is immiscible with said exterior phase. The components of the feed stream permeate through said exterior phase to the interior phase of the emulsion, wherein a reactant is maintained that will react with the permeable components converting them to a nonpermeable form and thus maintaining a concentration gradient across the exterior phase. See, for example, U.S. Pat. No. 3,617,546 and copending application 174,990, filed Aug. 25, 1971, now U.S. Pat. No. 3,779,907. In these processes, the emulsions utilized, unlike the emulsions utilized in forming the reactive products of the instant invention, are preferably formulated to be of sufficiently different density, than the continuous phase (feedstream), so as to separate easily from the feed-stream when agitation is ceased. Also, the exterior phase is selected to allow an efficient rate of permeation of feestream components, while the exterior phase of the emulsions utilized in the preparation of the instant reactive products, must be substantially impermeable.